Acoustic monitor

Abstract

An electronic monitor is disclosed which continuously monitors the sound emanating from rotating machinery, non-rotating equipment, or any other sound-producing process or environment, as a means of detecting abnormalities and thus determining the operating condition thereof. The monitor continuously computes the power spectrum of the monitored sound and has two modes of operation: learn and operate. The monitor is placed in the learn mode during a time when the machine or process to be monitored is known to be operating normally. During the learn mode, the maximum and minimum acoustic power output from each of a plurality of digital bandpass filters is continuously maintained and updated in data memory as the acoustic signature of the machine or process being monitored. During the operate mode, the monitor continuously compares the real-time filter outputs with the acoustic signature stored during the learn mode and activates a panel lamp and relay if the output of any of the bandpass filters deviates from the upper or lower decibel limits of the acoustic signature by more than the setting of the corresponding front panel sensitivity selector switch. In its preferred form, the monitor is capable of storing and utilizing up to five acoustic signatures, selectable by either an operator or a host controller, with the signatures being stored in non-volatile data memory. Two alarm levels are provided by the monitor: warning, to indicate a developing fault, and danger, to indicate a situation requiring immediate corrective action.